Llyn Barfog, or the Bearded Lake, is the setting for a particularly adventurous encounter between King Arther and the lake monster.
A great terrible monster, the "avanc", lived in the lake. From there it would emerge and terrorise the surrounding countryside. Arthur determined to put a stop to this, he arrived at the lake and lassoed the avanc with a hefty chain. Arthurs sturdy horse (sometimes called Llamrai) hauled the enchained monster from the lake and Arthur coulsd then kill it. Close to Llyn Barfog is a hoof-print etched deep into the rock, which is supposedly made by the horse when it was hauling the monster from the lake (Carn March Arthur, the Stone of Arthur's Horse).
The avanc has been described by different sources as a dragon, a crocodile,
and a beaver. The lake at Llyn Barfog is very small today to have held a monster,
but Llyn Barfog could have been much larger in King Arthur's day.
Arthurian Sites in Wales